Exterior aircraft light units are provided for a variety of purposes, such as for illumination, for signalling purposes, and for assessing the environment, for example in the course of landing and/or search maneuvers. Light units are known that emit light of different wavelengths. For example, it is known to provide search and landing lights that are capable of emitting visible light on the one hand and infrared light on the other hand. Other applications also call for two or more lighting modes with the emission of light of different wavelengths, due to particular application requirements and/or due to regulatory requirements. It may be desired to have corresponding emission characteristics of the light unit for the different wavelengths. Known light units therefore provide two optical structures, contained in one light unit. In particular, a first light source with a first wavelength is provided with one or more optical elements for shaping the emission characteristics of the first optical structure. A second light source with a second wavelength is provided with one or more optical elements for shaping the emission characteristics of the second optical structure. The optical elements are shaped and arranged in such a way that the two optical structures have corresponding emission characteristics. In the finished light unit, the two optical structures are placed adjacent to each other, usually in a common housing. The space requirements of such a light unit have been found to not be satisfactory.
Accordingly, it would be beneficial to provide an exterior aircraft light unit that has reduced space requirements. Further, it would be beneficial to provide a method of operating such an exterior aircraft light unit.